But he’s not convinced that climate change will result in the cataclysmic future predicted by forecasters.

“I wouldn’t call myself a denier, but I am skeptical about the gravity of the thing,” he said. “I’m trying to look at the facts and say what’s the deal here. And from what I’m seeing the consensus of scientists is not as pervasive as you describe.”

Walzel’s views open a window on how and why climate skepticism persists, despite mounting evidence that global warming not only poses a serious threat to the planet but is already doing damage. In Houston, long the unofficial capital of the world’s oil and gas industry, such strains of thought are particularly persistent, often grounded in the work of a small cadre of scientists who fixate on legitimate uncertainties within climate science.

They do not question the fundamental notion that greenhouse gas emissions are raising global temperatures but rather that it will all end in catastrophe. Dismissed as kooks or contrarians, these scientists continue to find followings among those like Walzel who believe if the world is going to shift from fossil fuels in just a matter of decades, we better be certain on the science.

Go to NASA’s website, and it states 97 percent of published climate scientists agree that manmade carbon emissions have caused the planet to warm over the past century. But once you get past the consensus that the planet is warming faster than it would naturally, agreement fractures over how fast polar ice caps are melting or whether climate change will cause more hurricanes and heat waves — hugely complex questions that require looking decades or centuries into the future.

Climate skeptics, or realists as they prefer to be called, fixate on the details under debate, even though the overwhelming the majority of climate scientists agree that global warming will go very badly unless mankind takes immediate action.